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Name: XPC Services
ID: T1559.003
Tactics:
Technique:
XPC Services (Cross Process Communication Services) is a sub-technique categorized under technique T1559 (Inter-Process Communication) within the MITRE ATT&CK framework. XPC services are native macOS mechanisms that facilitate secure inter-process communication and privilege separation. Attackers exploit XPC services to execute unauthorized commands or code, escalate privileges, or achieve persistence by leveraging legitimate communication channels between applications and processes.
XPC is a macOS-specific inter-process communication (IPC) mechanism designed to securely exchange data between processes. Apple introduced XPC to enhance security by isolating tasks into separate processes and restricting their privileges. However, attackers can exploit XPC services due to their inherent trust and legitimate use within macOS.
Technical details include:
XPC services typically reside within an application's bundle under Contents/XPCServices/.
Communication occurs via plist-based messages exchanged through XPC APIs provided by Apple.
Attackers may abuse existing XPC services or create malicious XPC services to execute arbitrary code or commands.
Malicious actors may inject or hijack legitimate XPC services to escalate privileges, maintain persistence, or evade detection.
XPC services run under the context of their hosting application, potentially allowing attackers to inherit elevated privileges.
Attackers may craft specific XPC messages to exploit vulnerabilities in applications or system services, causing unintended behavior or code execution.
Real-world procedures attackers might follow:
Identify vulnerable or misconfigured XPC services on the target macOS system.
Craft malicious XPC messages or payloads designed to trigger unintended functionality or exploit vulnerabilities.
Hijack or inject malicious code into existing legitimate XPC services.
Create malicious XPC services within legitimate application bundles to maintain persistence.
Leverage compromised XPC services to escalate privileges and perform lateral movement within the target environment.
Attackers commonly utilize XPC Services in various phases of an attack lifecycle, including:
Persistence: Attackers can implant malicious XPC services within legitimate application bundles to ensure persistence across reboots.
Privilege Escalation: Exploiting vulnerabilities or misconfigurations in XPC services can allow attackers to escalate privileges from standard user accounts to root or higher privileges.
Defense Evasion: Leveraging legitimate XPC services helps attackers blend malicious activities with normal operating system behavior, complicating detection.
Execution: Attackers may execute arbitrary commands or payloads through compromised or malicious XPC services.
Lateral Movement: Once a foothold is established, attackers may exploit XPC services to move laterally between applications and processes within macOS environments.
Detection of malicious use of XPC services involves monitoring and analyzing various aspects of macOS behavior, including:
Process Monitoring:
Identify unusual process executions or abnormal parent-child relationships involving XPC services.
Monitor processes spawned from unexpected locations or application bundles.
File System Monitoring:
Detect new or modified XPC services within application bundles (Contents/XPCServices/).
Monitor file integrity and changes within application directories, especially after suspicious activity.
Network Monitoring:
Identify unusual network connections or outbound traffic initiated by XPC-related processes.
Endpoint Detection and Response (EDR):
Use macOS-specific EDR solutions to detect suspicious XPC service interactions and behaviors.
Analyze logs and telemetry data from endpoints for anomalous XPC service communications.
Audit Logging:
Enable macOS audit logs to capture detailed events related to XPC service creation, execution, and communication.
Analyze audit logs regularly for anomalies and suspicious patterns.
Specific Indicators of Compromise (IoCs):
Unexpected XPC service binaries or bundles appearing in application directories.
Unusual plist files or configuration files associated with XPC services.
Anomalous XPC communication patterns between processes.
Suspicious processes spawned by XPC services, especially those with elevated privileges.
Detecting malicious exploitation of XPC services is crucial due to potential severe impacts on systems and networks, including:
Privilege Escalation:
Attackers may escalate privileges and gain root-level access, significantly increasing their control over compromised systems.
Persistence and Long-Term Access:
Malicious XPC services can provide attackers persistent and stealthy access, making remediation challenging.
Data Exfiltration:
Attackers may leverage compromised XPC services to exfiltrate sensitive information, credentials, or intellectual property.
Defense Evasion and Stealth:
Abuse of legitimate macOS mechanisms like XPC services allows attackers to evade traditional detection methods, increasing dwell time.
Operational Impact:
Compromise of XPC services can disrupt legitimate system functionality, degrade performance, and reduce system stability.
Early detection and response to malicious XPC service activity can significantly reduce attacker dwell time, minimize potential damage, and protect critical assets and sensitive data.
Real-world examples illustrating malicious usage of XPC services:
OSX.Dok Malware:
Utilized malicious XPC services to establish persistence and perform man-in-the-middle attacks, intercepting encrypted communications.
Installed a malicious XPC service within legitimate application bundles to evade detection and maintain long-term access.
XCSSET Malware:
Leveraged XPC services to inject malicious code into legitimate macOS applications like Xcode, allowing attackers to spread malware through software development environments.
Exploited XPC communications to execute arbitrary commands and steal sensitive information, including browser cookies and credentials.
EvilQuest (ThiefQuest) Malware:
Incorporated malicious XPC services to perform ransomware and data theft activities.
Used compromised XPC services to evade detection, escalate privileges, and maintain persistent control over infected macOS systems.
These examples demonstrate attackers' ability to exploit XPC services effectively, underscoring the importance of robust detection mechanisms and proactive monitoring strategies.
XPC Services [T1559.003]